Advanced find (algorithms)

PdfForQtLib/sources/pdfcompiler.h

@@ -92,7 +92,7 @@ private:
     std::map<PDFInteger, CompileTask> m_tasks;
 };
 
-class PDFAsynchronousTextLayoutCompiler : public QObject
+class PDFFORQTLIBSHARED_EXPORT PDFAsynchronousTextLayoutCompiler : public QObject
 {
     Q_OBJECT
 
@@ -130,6 +130,9 @@ public:
     /// \p textLayoutChanged is emitted.
     void makeTextLayout();
 
+    /// Returns true, if text layout is ready
+    bool isTextLayoutReady() const { return m_textLayouts.has_value(); }
+
 signals:
     void textLayoutChanged();
 

PdfForQtLib/sources/pdfdrawspacecontroller.cpp

@@ -994,6 +994,7 @@ QRectF PDFDrawWidgetProxy::fromDeviceSpace(const QRectF& rect) const
 void PDFDrawWidgetProxy::onTextLayoutChanged()
 {
     emit repaintNeeded();
+    emit textLayoutChanged();
 }
 
 bool PDFDrawWidgetProxy::isBlockMode() const

PdfForQtLib/sources/pdfdrawspacecontroller.h

@@ -276,6 +276,7 @@ public:
     const PDFCMSManager* getCMSManager() const;
     PDFProgress* getProgress() const { return m_progress; }
     void setProgress(PDFProgress* progress) { m_progress = progress; }
+    PDFAsynchronousTextLayoutCompiler* getTextLayoutCompiler() const { return m_textLayoutCompiler; }
 
     void setFeatures(PDFRenderer::Features features);
     void setPreferredMeshResolutionRatio(PDFReal ratio);
@@ -291,6 +292,7 @@ signals:
     void renderingError(PDFInteger pageIndex, const QList<PDFRenderError>& errors);
     void repaintNeeded();
     void pageImageChanged(bool all, const std::vector<PDFInteger>& pages);
+    void textLayoutChanged();
 
 private:
     struct LayoutItem

PdfForQtLib/sources/pdftextlayout.cpp

@@ -1,4 +1,4 @@
-//    Copyright (C) 2019 Jakub Melka
+//    Copyright (C) 2019-2020 Jakub Melka
 //
 //    This file is part of PdfForQt.
 //
@@ -593,4 +593,170 @@ QDataStream& operator>>(QDataStream& stream, PDFTextLayoutSettings& settings)
     return stream;
 }
 
+PDFTextSelection::PDFTextSelection(PDFTextSelectionItems&& items) :
+    m_items(qMove(items))
+{
+
+}
+
+PDFFindResults PDFTextFlow::find(const QString& text, Qt::CaseSensitivity caseSensitivity) const
+{
+    PDFFindResults results;
+
+    int index = m_text.indexOf(text, 0, caseSensitivity);
+    while (index != -1)
+    {
+        PDFFindResult result;
+        result.matched = text;
+        result.textSelectionItems = getTextSelectionItems(index, text.length());
+        result.context = getContext(index, text.length());
+
+        if (!result.textSelectionItems.empty())
+        {
+            results.emplace_back(qMove(result));
+        }
+
+        index = m_text.indexOf(text, index + 1, caseSensitivity);
+    }
+
+    return results;
+}
+
+void PDFTextFlow::merge(const PDFTextFlow& next)
+{
+    m_text += next.m_text;
+    m_characterPointers.insert(m_characterPointers.end(), next.m_characterPointers.cbegin(), next.m_characterPointers.cend());
+}
+
+PDFTextFlows PDFTextFlow::createTextFlows(const PDFTextLayout& layout, FlowFlags flags, PDFInteger pageIndex)
+{
+    PDFTextFlows result;
+
+    if (!flags.testFlag(SeparateBlocks))
+    {
+        result.emplace_back();
+    }
+
+    QString lineBreak(" ");
+    if (flags.testFlag(AddLineBreaks))
+    {
+#if defined(Q_OS_WIN)
+        lineBreak = QString("\r\n");
+#elif defined(Q_OS_UNIX)
+        linebreak = QString("\n");
+#elif defined(Q_OS_MAC)
+        lineBreak = QString("\r");
+#else
+        static_assert(false, "Fix this code!");
+#endif
+    }
+
+    size_t textBlockIndex = 0;
+    for (const PDFTextBlock& textBlock : layout.getTextBlocks())
+    {
+        PDFTextFlow currentFlow;
+
+        size_t textLineIndex = 0;
+        for (const PDFTextLine& textLine : textBlock.getLines())
+        {
+            const TextCharacters& characters = textLine.getCharacters();
+            for (size_t i = 0, characterCount = characters.size(); i < characterCount; ++i)
+            {
+                const TextCharacter& currentCharacter = characters[i];
+                if (i > 0 && !currentCharacter.character.isSpace())
+                {
+                    // Jakub Melka: try to guess space between letters
+                    const TextCharacter& previousCharacter = characters[i - 1];
+                    if (!previousCharacter.character.isSpace() && QLineF(previousCharacter.position, currentCharacter.position).length() > previousCharacter.advance * 1.1)
+                    {
+                        currentFlow.m_text += QChar(' ');
+                        currentFlow.m_characterPointers.emplace_back();
+                    }
+                }
+
+                currentFlow.m_text += currentCharacter.character;
+
+                PDFCharacterPointer pointer;
+                pointer.pageIndex = pageIndex;
+                pointer.blockIndex = textBlockIndex;
+                pointer.lineIndex = textLineIndex;
+                pointer.characterIndex = i;
+                currentFlow.m_characterPointers.emplace_back(qMove(pointer));
+            }
+
+            // Remove soft hyphen, if it is enabled
+            if (flags.testFlag(RemoveSoftHyphen) && !characters.empty() && currentFlow.m_text.back() == QChar(QChar::SoftHyphen))
+            {
+                currentFlow.m_text.chop(1);
+                currentFlow.m_characterPointers.pop_back();
+
+                if (!flags.testFlag(AddLineBreaks))
+                {
+                    // Do not add single empty space - because soft hypen probably breaks a word
+                    ++textLineIndex;
+                    continue;
+                }
+            }
+
+            // Add line break
+            currentFlow.m_text += lineBreak;
+            currentFlow.m_characterPointers.insert(currentFlow.m_characterPointers.end(), lineBreak.length(), PDFCharacterPointer());
+
+            ++textLineIndex;
+        }
+
+        // If we are producing separate blocks, then make flow for each
+        // text block, otherwise join flows.
+        if (flags.testFlag(SeparateBlocks))
+        {
+            result.emplace_back(qMove(currentFlow));
+        }
+        else
+        {
+            result.back().merge(currentFlow);
+        }
+
+        ++textBlockIndex;
+    }
+
+    return result;
+}
+
+PDFTextSelectionItems PDFTextFlow::getTextSelectionItems(size_t index, size_t length) const
+{
+    PDFTextSelectionItems items;
+
+    auto it = std::next(m_characterPointers.cbegin(), index);
+    auto itEnd = std::next(m_characterPointers.cbegin(), index + length);
+    s
+
+    return items;
+}
+
+QString PDFTextFlow::getContext(size_t index, size_t length) const
+{
+    Q_ASSERT(length > 0);
+
+    while (index > 0 && m_characterPointers[index - 1].hasSameLine(m_characterPointers[index]))
+    {
+        --index;
+        ++length;
+    }
+
+    size_t currentEnd = index + length - 1;
+    size_t last = m_characterPointers.size() - 1;
+    while (currentEnd < last && m_characterPointers[currentEnd].hasSameLine(m_characterPointers[currentEnd + 1]))
+    {
+        ++currentEnd;
+        ++length;
+    }
+
+    return m_text.mid(int(index), int(length));
+}
+
+bool PDFCharacterPointer::hasSameLine(const PDFCharacterPointer& other) const
+{
+    return pageIndex == other.pageIndex && blockIndex == other.blockIndex && lineIndex == other.lineIndex;
+}
+
 }   // namespace pdf

PdfForQtLib/sources/pdftextlayout.h

@@ -1,4 +1,4 @@
-//    Copyright (C) 2019 Jakub Melka
+//    Copyright (C) 2019-2020 Jakub Melka
 //
 //    This file is part of PdfForQt.
 //
@@ -24,9 +24,11 @@
 #include <QPainterPath>
 
 #include <set>
+#include <compare>
 
 namespace pdf
 {
+class PDFTextLayout;
 
 struct PDFTextCharacterInfo
 {
@@ -152,6 +154,100 @@ private:
 
 using PDFTextBlocks = std::vector<PDFTextBlock>;
 
+/// Character pointer points to some character in text layout.
+/// It also has page index to decide, which page the pointer points to.
+struct PDFCharacterPointer
+{
+    auto operator<=>(const PDFCharacterPointer&) const = default;
+
+    /// Returns true, if character pointer is valid and points to the correct location
+    bool isValid() const { return pageIndex > -1; }
+
+    /// Returns true, if character belongs to same line
+    bool hasSameLine(const PDFCharacterPointer& other) const;
+
+    int pageIndex = -1;
+    size_t blockIndex = 0;
+    size_t lineIndex = 0;
+    size_t characterIndex = 0;
+};
+
+using PDFTextSelectionItem = std::pair<PDFCharacterPointer, PDFCharacterPointer>;
+using PDFTextSelectionItems = std::vector<PDFTextSelectionItem>;
+
+/// Text selection, can be used across multiple pages.
+class PDFTextSelection
+{
+public:
+    explicit PDFTextSelection(PDFTextSelectionItems&& items);
+
+private:
+    PDFTextSelectionItems m_items;
+};
+
+struct PDFFindResult
+{
+    /// Matched string during search
+    QString matched;
+
+    /// Context (text before and after match)
+    QString context;
+
+    /// Matched selection (can be multiple items, if selection
+    /// is spanned between multiple blocks)
+    PDFTextSelectionItems textSelectionItems;
+};
+using PDFFindResults = std::vector<PDFFindResult>;
+
+class PDFTextFlow;
+using PDFTextFlows = std::vector<PDFTextFlow>;
+
+/// This class represents a portion of continuous text on the page. It can
+/// consists of multiple blocks (which follow reading order).
+class PDFTextFlow
+{
+public:
+
+    enum FlowFlag
+    {
+        None                = 0x0000,
+        SeparateBlocks      = 0x0001, ///< Create flow for each block
+        RemoveSoftHyphen    = 0x0002, ///< Removes 'soft hyphen' unicode character from end-of-line (character 0x00AD)
+        AddLineBreaks       = 0x0004, ///< Add line break characters to the end of line
+    };
+    Q_DECLARE_FLAGS(FlowFlags, FlowFlag)
+
+    /// Finds simple text in current text flow. All text occurences are returned.
+    /// \param text Text to be found
+    /// \param caseSensitivity Case sensitivity
+    PDFFindResults find(const QString& text, Qt::CaseSensitivity caseSensitivity) const;
+
+    /// Merge data from \p next flow (i.e. connect two consecutive flows)
+    void merge(const PDFTextFlow& next);
+
+    /// Creates text flows from text layout, according to creation flags.
+    /// \param layout Layout, from which is text flow created
+    /// \param flags Flow creation flags
+    /// \param pageIndex Page index
+    static PDFTextFlows createTextFlows(const PDFTextLayout& layout, FlowFlags flags, PDFInteger pageIndex);
+
+private:
+    /// Returns text selection from index and length. Returned text selection can also
+    /// be empty (for example, if only single space character is selected, which has
+    /// no counterpart in real text)
+    /// \param index Index of text selection subrange
+    /// \param length Length of text selection
+    PDFTextSelectionItems getTextSelectionItems(size_t index, size_t length) const;
+
+    /// Returns context for text selection (or empty string, if text selection is empty)
+    /// \param index Index of text selection subrange
+    /// \param length Length of text selection
+    QString getContext(size_t index, size_t length) const;
+
+    QString m_text;
+    std::vector<PDFCharacterPointer> m_characterPointers;
+};
+
 /// Text layout of single page. Can handle various fonts, various angles of lines
 /// and vertically oriented text. It performs the "docstrum" algorithm.
 class PDFTextLayout